Contact-rich Manipulation

A manipulation task that needs sustained contact with an object or surface, with careful control of contact force.

Contact-rich manipulation describes tasks where a robot maintains continuous or repeated contact with an object or environment, and must control contact force, explicitly or implicitly, to succeed — peg-in-hole assembly, tightening a nut, plugging in a cable, wiping a table, massage. A 2022 survey by Markku Suomalainen and colleagues in Robotics and Autonomous Systems splits this into two kinds: tasks that inherently require contact, and tasks that actively use contact to remove position uncertainty, such as sliding a part along a surface into a hole. The difficulty lies in tight tolerances, contact states that are hard to see visually, and friction and collisions that are hard to simulate accurately. Common approaches use impedance control or force control, making the arm behave like a spring that yields to external force, paired with force/torque sensors or tactile sensors; learning-based methods instead feed force or tactile signals into the policy as input.

ExampleThreading a nut onto a bolt with a robot arm: once aligned, the robot must apply axial pressure while rotating — too much force jams it, too little and it slips. NVIDIA's Factory simulation framework (2022) uses nut-and-bolt assembly as one of its main scenarios.

Also called

Manipulation in Contact

Related

Peg-in-Hole Insertion · Force Control · Impedance Control · Tactile Sensor · Dexterous Manipulation · Robotic Assembly

Sources

A Survey of Robot Manipulation in Contact (arXiv 2112.01942)
Factory: Fast Contact for Robotic Assembly (arXiv 2205.03532)